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Just based off pure win-loss records, if I asked you which teams have been the best in 2018, I would think the Yankees and Red Sox would be the first two teams to pop into your head. If I asked you to name some of the best teams ever, I’m sure the usual suspects, such as the 1927 Yankees, 1975 Reds, 1998 Yankees, and the 2001 Mariners would come to mind. I’m also fairly sure most of the general consensus wouldn’t put any of these 2018 teams in the same room as those historically great teams.
Now what if I told you there was in fact a historically great team playing in the current progression of this 2018 season, and that they weren’t even leading their respective league in winning percentage, let alone currently ranking third in that department.
But this so happens to be true. The best team in baseball so far this year hasn’t been the Yankees and it hasn’t been the Red Sox. It’s the Astros, and they might be the best team in the history of modern baseball.
Now that my overly-dramatic intro is finished, let’s get down to business. The Astros are good (bold, I know right). Everyone knows this. In the time of when this was written, they own a 12-game winning streak and sit atop the AL West by two games.
With that out of the way, this brings up the fair question of why would a team that is currently the third best team in the major leagues in terms of winning percentage be considered an all-time great team? Well to start, the remarkable start by the pitching staff is no secret. As it stands, their starting rotation would have the highest K% in MLB history and their bullpen would have the second highest mark in history (only behind the 2018 Yankees). The offense is no issue too, pacing to lead the majors in wRC+. All these tidbits help the argument, but the main reason for this opinion lies in the great world of run differential, or pythagorean winning percentage to a deeper level.
To get right to it, no team in the history of modern baseball (I’m going back to 1960 for this study), has ever finished the season with a higher per game run differential greater than two. The highest ever was the 1998 Yankees, sitting at +1.907. The 2018 Astros are currently sitting at +2.139, so there is definitely a fair chance they could achieve this.
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Breaking that per game run differential into a scaled measurement of pythagorean winning percentage, the Astros come out as having an expected winning percentage of 72.2%. This tops all major league teams easily, with the Cubs coming in next at 65.4%. The Astros separation between their pythagorean winning percentage and actual winning percentage of 65.3% also leads the majors. Let’s see how that pythagorean record compares with some of the great teams of the modern-era.
Top 20 Pythagorean Winning Percentages (1960-)
Season | Team | W | L | Actual WP% | Pythag. WP% |
---|---|---|---|---|---|
Season | Team | W | L | Actual WP% | Pythag. WP% |
2018 | Astros | 47 | 25 | 65.28% | 72.19% |
1969 | Orioles | 109 | 53 | 67.28% | 67.74% |
2001 | Mariners | 116 | 46 | 71.60% | 66.99% |
1998 | Yankees | 114 | 48 | 70.37% | 66.79% |
2016 | Cubs | 103 | 58 | 63.98% | 66.30% |
2017 | Indians | 102 | 60 | 62.96% | 66.22% |
1975 | Reds | 108 | 54 | 66.67% | 65.74% |
1974 | Dodgers | 102 | 60 | 62.96% | 65.43% |
2018 | Cubs | 40 | 27 | 59.70% | 65.41% |
1998 | Braves | 106 | 56 | 65.43% | 65.40% |
1998 | Astros | 102 | 60 | 62.96% | 65.06% |
1971 | Orioles | 101 | 57 | 63.92% | 64.77% |
2018 | Red Sox | 48 | 24 | 66.67% | 64.54% |
2018 | Yankees | 46 | 20 | 69.70% | 64.40% |
1995 | Indians | 100 | 44 | 69.44% | 64.29% |
1976 | Phillies | 101 | 61 | 62.35% | 64.25% |
1970 | Orioles | 108 | 54 | 66.67% | 64.17% |
1993 | Braves | 104 | 58 | 64.20% | 63.94% |
2001 | Athletics | 102 | 60 | 62.96% | 63.89% |
1968 | Tigers | 103 | 59 | 63.58% | 63.68% |
It goes without saying that the Astros would totally be fine playing under the level of their pythagorean winning percentage all year, pacing for a 106-56 record at the moment (pace of their pythagorean record is 117-45). But we can probably expect some forward progression in the second half of this season. This development comes as bad news to the Mariners. With the Astros only leading the AL West by a mere 1.5 games, it would seem as if they would have more than a fighting chance at the division with more than half the season left. But, if the Astros start pulling closer to their expected record, they’ll have no chance. It’s also worth noting while the Astros are performing at a historical level, the Mariners are over-performing at a historical pace.
Largest pythagorean winning percentage over-performances (1960-)
Season | Team | W | L | Actual WP% | Pythag. WP% | Differential |
---|---|---|---|---|---|---|
Season | Team | W | L | Actual WP% | Pythag. WP% | Differential |
2018 | Mariners | 46 | 25 | 64.79% | 54.24% | 10.54% |
1981 | Reds | 66 | 42 | 61.11% | 52.40% | 8.71% |
2016 | Rangers | 95 | 67 | 58.64% | 50.48% | 8.17% |
2004 | Yankees | 101 | 61 | 62.35% | 54.71% | 7.63% |
2008 | Angels | 100 | 62 | 61.73% | 54.20% | 7.53% |
1972 | Mets | 83 | 73 | 53.21% | 45.92% | 7.29% |
1984 | Mets | 90 | 72 | 55.56% | 48.36% | 7.19% |
1970 | Reds | 102 | 60 | 62.96% | 55.82% | 7.14% |
2017 | Padres | 71 | 91 | 43.83% | 36.71% | 7.11% |
1981 | Orioles | 59 | 46 | 56.19% | 49.16% | 7.03% |
2012 | Orioles | 93 | 69 | 57.41% | 50.45% | 6.96% |
2007 | Diamondbacks | 90 | 72 | 55.56% | 48.75% | 6.81% |
2005 | Diamondbacks | 77 | 85 | 47.53% | 40.74% | 6.79% |
1961 | Reds | 93 | 61 | 60.39% | 53.78% | 6.61% |
1994 | Pirates | 53 | 61 | 46.49% | 40.22% | 6.27% |
1997 | Giants | 90 | 72 | 55.56% | 49.48% | 6.07% |
2009 | Mariners | 85 | 77 | 52.47% | 46.47% | 6.00% |
1977 | Orioles | 97 | 64 | 60.25% | 54.35% | 5.90% |
1978 | Reds | 92 | 69 | 57.14% | 51.42% | 5.72% |
2016 | Phillies | 71 | 91 | 43.83% | 38.18% | 5.64% |
It’s hard to improve the following season after a World Series win. Most teams actually start a decline. But the Astros are doing just the opposite of that. They’re getting better. Significantly better. And their improvement might just lead them to becoming one of the greater teams in the history of modern baseball.
*All graphs are as of June 17th